Synthesis and characterisation of mono-acetylide and unsymmetrical bis-acetylide complexes of ruthenium and osmium: X-ray structure determinations on [(dppe)2Ru(Cl)(C≡C-C6H4-p-NO 2)], [(dppe)2Ru(Cl)(C≡C-C6H3-o-CH 3-p-NO2)]

Article abstract of DOI:10.1016/S0022-328X(98)01123-1

The synthesis of a series of metal mono-acetylides trans-[(dppe)₂Ru(Cl)(C≡C-R)] (R = C₆H₄-p-C₆H₅, C₆H₄-p-CH₃, C₆H₄-p-NO₂, C₆H₃-o-CH₃-p-NO₂, dppe = Ph₂PCH₂CH₂PPh₂), and unsymmetrical metal bis-acetylides trans-[(dppm)₂M(C≡C-R)(C≡C-R′)]; (M = Ru, Os; R = C₆H₄-p-NO₂, R′ = C₆H₅, C₆H₄-p-CH₃; R = C₆H₅, R′ = C₆H₄-p-C₆H₃) using a variety of σ-acetylide coupling reactions is reported. Three compounds have been structurally characterised, including the unsymmetrical trans-[(dppm)₂Os(C≡C-R)(C≡C-R′)] (R = C₆H₄-p-CH₃, R′ = C₆H₄-p-NO₂] which shows the 'rigid-rod' nature of the acetylide-metal-acetylide linkage. The electrochemistry of symmetrical and unsymmetrical Ru(II) complexes demonstrates the role of the acetylide and the auxiliary ligands in determining the ease of oxidation at the metal centre whilst UV-vis spectral changes illustrate the influence of electron-withdrawing and -donating ligands.

Full text of DOI:10.1016/S0022-328X(98)01123-1

Journal of Organometallic Chemistry 578 (1999) 198–209
Synthesis and characterisation of mono-acetylide and unsymmetrical
bis-acetylide complexes of ruthenium and osmium: X-ray structure
determinations on [(dppe)2Ru(Cl)(CꢀC–C6H4-p-NO2)],
[(dppe)2Ru(Cl)(CꢀC–C6H3-o-CH3-p-NO2)] and
[(dppm)2Os(CꢀC–C6H4-p-CH3)(CꢀC–C6H4-p-NO2)]
Muhammad Younus a, Nicholas J. Long a,*, Paul R. Raithby b, Jack Lewis b, Nicola A. Page b,
Andrew J.P. White a, David J. Williams a, Michael C.B. Colbert b, Andrew J. Hodge b,
Muhammad S. Khan c, David G. Parker d
a Department of Chemistry, Imperial College of Science, Technology and Medicine, South Kensington, SW7 2AY, London, UK
b Department of Chemistry, Lensfield Road, CB2 1EW, Cambridge, UK
c Department of Chemistry, College of Science, Sultan-Qaboos Uni6ersity, 123 Al-Khod, Oman
d ICI Group R & T Affairs, P.O. 90, Wilton Centre, TS90 8JE, Middlesborough, Cle6eland, UK
Received 13 July 1998
Abstract
The synthesis of a series of metal mono-acetylides trans-[(dppe)2Ru(Cl)(CꢀC–R)] (R=C6H4-p-C6H5, C6H4-p-CH3, C6H4-p-
NO2, C6H3-o-CH3-p-NO2, dppe=Ph2PCH2CH2PPh2), and unsymmetrical metal bis-acetylides trans-[(dppm)2M(CꢀC–R)(CꢀC–
R%)]; (M=Ru, Os; R=C6H4-p-NO2, R%=C6H5, C6H4-p-CH3; R=C6H5, R%=C6H4-p-CH3) using a variety of s-acetylide
coupling reactions is reported. Three compounds have been structurally characterised, including the unsymmetrical trans-
[(dppm)2Os(CꢀC–R)(CꢀC–R%)] (R=C6H4-p-CH3, R%=C6H4-p-NO2] which shows the ‘rigid-rod’ nature of the acetylide-metal-
acetylide linkage. The electrochemistry of symmetrical and unsymmetrical Ru(II) complexes demonstrates the role of the acetylide
and the auxiliary ligands in determining the ease of oxidation at the metal centre whilst UV–vis spectral changes illustrate the
influence of electron-withdrawing and -donating ligands. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Ruthenium; Osmium; Acetylide; Electrochemistry
been the requirement of new products for the materials
industry and these linear, delocalised species are poten-
tially liquid crystalline [3], conductive (with electron
transfer) [4], and third-order non-linear optical materi-
als [5]. Compounds need to be processable and charac-
terisable and it is clear that greater variation needs to
be introduced into the p-conjugated bi- or multi-metal-
lic systems [6], e.g. incorporation of metals of different
oxidation state and variation of phosphines (the bulkier
the phosphine, the greater the solubility of the poly-
mer). Our group has recently formed species featuring
d6, d7 and d8 metals in order to increase the flexibility
of the systems [7].
1. Introduction
The development of synthetic routes towards
organometallic metal-acetylide oligomers and polymers
has progressed rapidly following the initial reports on
Group 10 metal-acetylide polymers [1]. Since then,
there has been a burgeoning range of ligands and
metals incorporated into these ligand systems [2]. The
driving force behind these synthetic developments has
* Corresponding author. Tel.: +44-171-5945-781; fax: +44-171-
5945-804.
E-mail address: n.long@ic.ac.uk (N.J. Long)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01123-1

M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
199
Design of molecules with symmetric and unsymmet-
ric donor/acceptor end groups at para positions contin-
ues to draw much attention due to their intriguing
third- and second-order nonlinear optical behaviour [8].
Group 8 metal acetylides of the type trans-[(L–
L)2M(Cl)(CꢀC–R)] (L–L=dppm and/or dppe; M=
Ru and/or Os) has recently been reported by several
groups [9,10] including ourselves [6j, 7d–h]. Following
our previous work, we have synthesised and studied the
coupling reactions of these complexes with various
acetylenic ligands which give rise to unsymmetrical
bis-acetylide complexes. We, therefore report here, the
synthesis of a series of mono-acetylide complexes of the
{Ru(II)(dppe)} fragment along with some bis-acetylide
complexes of {ML2} (M=Ru, Os; L=dppm, dppe) in
which the metal fragment contains symmetric and un-
symmetric s-acetylide linkages in a trans configuration.
Single crystal X-ray determinations have been made of
the mono-acetylide complexes trans-[(dppe)2Ru(Cl)-
(CꢀC–C6H4-p-NO2)] and trans-[(dppe)2Ru(Cl)(CꢀC–
C6H3-o-CH3-p-NO2)] and the unsymmetrical bis-
acetylide complex trans-[(dppm)2Os(CꢀC–C6H4-p-
NO2)(CꢀC–C6H4-p-CH3)]. All the complexes have been
fully characterised and in particular, studied for their
electrochemical and electronic properties.
Scheme 1. Synthesis of ruthenium(II) mono-acetylides.
acetylide complexes trans-[(dppe)2Ru(Cl)(CꢀC–R)]
(R=C6H4-p-CH3 1, C6H4-p-C6H5 2, C6H4-p-NO2 3,
C6H3-o-CH3-p-NO2 4) (Scheme 1). In recent reports,
Dixneuf et al. independently describe the synthesis of
trans-[(dppe)2Ru(Cl)(–CꢀC–R)] (R=H, nBu, Ph,
C6H4-p-OMe, C6H4-p-NO2) using cis-[(dppe)2RuCl2] as
the starting material [9d]. Although the reaction of
trans-[(dppe)2RuCl2] with terminal acetylenes is slower
than with the cis-analogues, the former material has
easier availability and gives high yielding selective syn-
theses of mono-acetylides.
2.1.2. Unsymmetrical bis-acetylides of Ru(II) and
Os(II)
Following our previous method, [6j] we have synthe-
sised a series of unsymmetrical bis-acetylides trans-
[(dppm)2Ru(CꢀCR)(–CꢀCR%)] (M=Ru and Os) by the
reaction of metal chloro-mono-acetylides with
trimethylstannyl acetylides. For example, when trans-
[(dppm)2Ru(Cl)(–CꢀC-p-C6H4–NO2)] was treated with
Me3SnCꢀCR (R=C6H5, C6H4-p-CH3) in THF, in the
presence of CuI, under reflux for 2 h, a mixture of
unsymmetrical bis-acetylides trans-[(dppm)2Ru(CꢀC-p-
C6H4–NO2)(CꢀCR)] (R=C6H5 7, C6H4-p-CH3 8) and
symmetrical bis-acetylide trans-[(dppm)2Ru(–CꢀC-p-
C6H4-NO2)2] 9 was formed (Scheme 2) (complexes 7
and 9 have recently been formed by a different method
in 30, and 62% yields, respectively [10b], whilst our
work was in progress). The products can be separated
by column chromatography on neutral grade II alu-
mina using hexane/dichloromethane mixtures as eluents
and the yields of the unsymmetrical acetylides were
much higher (ca. 50%) than the symmetrical one
(B20%). The symmetrical bis-acetylide may be formed
by a disproportion mechanism, and this has been ob-
2. Results and discussion
2.1. Synthetic studies
2.1.1. Mono-acetylides of ruthenium
Although aryl substituted mono-acetylide complexes
trans-[(dppm)2Ru(Cl)(CꢀC–R)]
(R=C6H4-p-CH3,
C6H4-p-C6H5, C6H4-p-NO2, C6H3-o-CH3-p-NO2), can
be formed in good yield by the reaction of cis-
[(dppm)2RuCl2] with terminal acetylenes [7e] using
Dixneuf’s route [9b], we found that this was not a good
route for formation of the Ru(dppe)2 analogues. This is
because, despite our efforts, cis-[(dppe)2RuCl2] could
not be synthesised in a pure form (it being contami-
nated with trans-[(dppe)2RuCl2]). The cis- to trans-iso-
merisation during the acetylide addition is believed to
be a driving force of the reaction however, the trans-
starting material [(dppe)2RuCl2] reacts with terminal
acetylenes albeit slowly [6j]. Therefore, trans-
[(dppe)2RuCl2] was treated with the terminal acetylenes
HCꢀCR (R=C6H4-p-CH3, C6H4-p-C6H5, C6H4-p-
NO2, C6H3-o-CH3-p-NO2) in CH2Cl2 in the presence of
two equivalents of NaPF6 for 5–7 days at room tem-
perature (r.t.), to form the vinylidene complexes
[(dppe)2(Cl)RuꢁCꢁC(H)(R)]+[PF6]− which were not
characterised but reacted in situ. After removal of
excess ligands by washing with hexane, one equivalent
of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in CH2Cl2
was added and stirring continued for 3 h to afford the
Scheme 2. Synthesis of unsymmetrical ruthenium(II) and osmium(II)
bis-acetylides.

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M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
Table 1
Infrared, 31P{1H}-NMR and mass spectra of ruthenium(II) and osmium(II) mono- and bis-acetylides
Complex
w(CꢀC)a (cm−1
)
31P{1H}-NMRb (ppm)
M+c
trans-[(dppe)2Ru(Cl)(CꢀC–C6H4-p-CH3)] 1
trans-[(dppe)2Ru(Cl)(CꢀC–C6H4-p-C6H5)] 2
trans-[(dppe)2Ru(Cl)(CꢀC–C6H4-p-NO2)] 3
trans-[(dppe)2Ru(Cl)(CꢀC–C6H3-o-CH3-p-NO2)] 4
trans-[(dppe)2Ru(CꢀC–C6H4-p-CH3)2] 5
2074
2071
2051
2029
2062
2043
−91.3
−91.3
−92.5
−91.4
−87.1
1048.2 (1048.5)
1110 (1110)
1079 (1079)
1094 (1093.5)
–
trans-[(dppe)2Ru(CꢀC–C6H4-p-NO2)2] 6
−88.2
–
trans-[(dppm)2Ru(CꢀC–C6H4-p-NO2)(CꢀC-C6H5)] 7
trans-[(dppm)2Ru(CꢀC–C6H4-p-NO2)(CꢀC–C6H4-p-CH3)] 8
trans-[(dppm)2Ru(CꢀC–C6H4-p-NO2)2] 9
trans-[(dppm)2Ru(CꢀC–C6H5)(CꢀC–C6H4-p-CH3)] 10
trans-[(dppm)2Os(CꢀC–C6H4-p-NO2)(CꢀC–C6H5)] 11
trans-[(dppm)2Os(CꢀC–C6H4-p-NO2)(CꢀC–C6H4p-CH3] 12
trans-[(dppm)2Os(CꢀC–C6H5(CꢀC–C64p-CH3 13
2054, 2079
2054, 2080
2052
−144.9
−145.0
−145.2
−144.5
−191.4
−191.4
−195.0
1116 (1116)
1131 (1130)
1162 (1161)
1083 (1085)
1209 (1207)
1218 (1221)
1178 (1175)
2069
2052, 2080
2051, 2083
2069
a IR spectra were recorded in CH2Cl2.
b 31P{1H}-NMR spectra were referenced to P(OMe)3.
c Calculated molecular ions are given in parentheses.
slow conversion of unsymmetrical to symmetrical
acetylides in solution was observed and was believed to
be accelerated in the presence of Me3SnCl. However, in
the case of ruthenium and osmium, no such conversion
was observed, even when unsymmetrical bis-acetylides
were refluxed in dichloromethane for 48 h in the pres-
ence of Me3SnCl.
Symmetrical and unsymmetrical bis-acetylides of
ruthenium [(depe)2Ru(CꢀC–C6H5)2], [(depe)2Ru(CꢀC–
C6H4-p-OMe)2] and [(depe)2Ru(CꢀC–C6H5)(CꢀC–
C6H4-p-OMe)] (depe=Et2PCH2CH2PEt2) complexes
have also been reported by Field and co-workers [6p].
These were formed as a mixture by the reaction trans-
[(depe)2RuCl2] with two different acetylenes, in the
presence of sodium methoxide. The amount of the
unsymmetrical bis-acetylides formed was dependent on
the ratio of the terminal acetylenes used in the
reactions.
served in analogous systems [9d, 10b] but surprisingly
in each case and also here, only one symmetrical bis-
acetylide species was observed as opposed to the two
that are possible. In a similar reaction, trans-[(dppm)2-
Ru(Cl)-(CꢀC–C6H5)] was reacted with Me3SnCꢀC-p-
C6H4–CH3 in THF to form trans-[(dppm)2Ru(CꢀC-p-
C6H4–CH3)(–CꢀC–C6H5)] 10 in 44% yield but no trace
of symmetrical product was observed in the reaction
mixture. Unsymmetrical osmium bis-acetylides trans-
[(dppm)2Os(CꢀC-p-C6H4–NO2)(CꢀCR)] (R=C6H5 11,
C6H4-p-CH3 12) and trans-[(dppm)2Os(CꢀC-p-C6H4–
CH3)(CꢀC–C6H5)] 13 were similarly prepared by the
reaction of osmium chloro-mono-acetylides with the
appropriate tin acetylides although the reactions were
slower than those of ruthenium analogues. The prod-
ucts were purified by column chromatography on neu-
tral grade II alumina using hexane/dichloromethane
mixtures as eluents followed by recrystallisation in a
solvent mixture of dichloromethane and hexane (1:1).
Unsymmetrical bis-acetylide complexes of the type
trans-[(dppe)2Ru(CꢀCR)(CꢀCR%)] (R=Ph, R=nBu;
R=Ph, R%=p-C6H4–NO2; R=nBu, R%=p-C6H4–
NO2; R=p-C6H4–OMe, R%=p-C6H4–NO2) can also
2.2. Spectroscopic characterisation
The w(CꢀC) stretching frequency is diagnostic in the
characterisation of metal acetylide complexes. All the
ruthenium and osmium acetylides showed a single
stretching frequency in the range of 2029–2081 cm−1
for w(CꢀC) bonds which confirms the trans configura-
tion of acetylides around metal atoms with respect to
other acetylides or chlorides (Table 1). In the case of
metal mono-acetylides, the w(CꢀC) stretching frequency
of the NO2-substituted aryl acetylides is lower in
wavenumber than those of phenyl or tolyl species. This
is due to the higher degree of electron delocalisation
when electron-withdrawing NO2 occupies the para posi-
tion of the aryl ring. Interestingly, when an electron
donating methyl group is added to the nitrophenyl
acetylides the frequency decreases. The w(CꢀC) stretch-
be
formed
by
the
reaction
of
[(dppe)2-
(Cl)RuꢁCꢁC(H)(R%)]+[PF6]− with HCꢀCR%, NaPF6
and NEt3 (reported by Touchard et al. independently
[9d] during the preparation of this manuscript). Follow-
ing
this
procedure,
[(dppm)2(Cl)RuꢁCꢁC(H)-
(Ph)]+[PF6]− was reacted with HCꢀC-p-C6H4–NO2.
Unsymmetrical bis-acetylide 7 (33%) and symmetrical
bis-acetylide 9 (15%) were obtained and purified by
column chromatography on alumina.
Unsymmetrical bis-acetylides of platinum, trans-
[(Et3P)2Pt(CꢀC–R)(CꢀCR%)] (R=Me, Ph; R%=H) were
first made by Sebald et al. [11] by the reaction of
trans-[(Et3P)2Pt(Cl)(–CꢀC–R)] with Me3SnCꢀCR%. A

M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
201
ing frequencies of the symmetrical bis-acetylides of
ruthenium are ca. 10 cm−1 lower than those of mono-
acetylides and in most cases, the unsymmetrical bis-
acetylides showed two different w(CꢀC) stretching
frequencies indicative of the different types of
acetylides.
large shift to lower wavenumber (160 nm for Ru and
189 nm for Os) which may be due to some contribution
from vinylidene-type structures (MꢁCꢁCꢁC–). Calcula-
tions on similar ruthenium bis-acetylide systems showed
that changing the CꢀC (acetylide) to CꢁC (vinylidene)
provides a better energy match between the p-orbital of
the ethylene and p-orbital of the phenyl ring. This
lowers the energy of the LUMO and the energy of the
HOMO is not greatly affected and thus decreases the
band gap [12a]. Substitution of the remaining chloride
of trans-[(dppm)2Ru(Cl)(CꢀC–R)] by a donor tolyl
acetylide did not have much (shifted to lower frequency
by only 7 nm) effect on the lowest energy band of the
complexes (Fig. 1). Replacement of the auxiliary phos-
phine Ph2PCH2PPh2 by Ph2PCH2CH2PPh2 did not
have a significant effect on the lowest energy band
either but this band was shifted significantly to a lower
wave number when ruthenium was replaced by os-
mium. The occurrence of significant solvatochromism is
often an indicator of a high molecular hyperpolarisabil-
ity, i, and has for example been demonstrated for some
conjugated organoferrocenes [13]. The solvatochromism
of the donor- and acceptor-based unsymmetrical ruthe-
nium and osmium bis-acetylides was studied by varying
solvents of different polarity and the results are listed in
Table 3. In each complex, a moderate shift to lower
frequency of the lowest energy band was observed and
osmium acetylides showed greater shift than ruthenium
species.
All the ruthenium and osmium acetylides showed
broad multiplets in the range ca. 6.7–7.8 ppm in their
1H-NMR spectra which are due to the phenyl protons
of the chelating phosphine ligands. For complexes 1–6,
multiplets appeared at ca. 2.6 ppm which we assign to
the CH2 protons of the ruthenium bound dppe ligand.
In the case of dppm bound ruthenium complexes 7–10,
the CH2 protons resonate at ca. 4.8 ppm. In most cases,
acetylide aromatic protons show the expected (AB)2
pattern. For example, complex 3 shows two sets of
doublets at 6.43 and 7.93 ppm with a coupling constant
3
of J(AB)=9 Hz. All the complexes displayed a singlet
in their 31P{1H}-NMR spectrum which again suggested
that the acetylide ligands adopt a trans configuration
with respect to the chloride or other acetylide. The
phosphorus atoms in trans-[(dppe)2RuCl2] resonate at
−96 ppm. This signal shifts downfield by ca. 4 ppm
when one Cl− is substituted by an acetylide, and it
resonates further downfield by ca. 6 ppm when the
second Cl− is substituted (Table 1). A similar trend
was observed in the spectra of the metal acetylide
complexes with dppm ligands and suggests that
acetylide ligands have greater p-electron accepting abil-
ity than that of the chloride ligands.
Most of the metal (Ru and Os) acetylide complexes
showed a molecular ion peak in their +FAB mass
spectra (Table 1). In some cases molecular ions were
not present but fragmented [M–CꢀC–R]+ ions were
observed indicating the presence of the complexes. In
the mass spectra of the complexes trans-
[(dppe)2Ru(Cl)(CꢀC–R)] 1–4, stepwise loss of chlorides
and acetylides was observed and in the spectra of the
corresponding bis-acetylides 5–6, stepwise loss of two
acetylide fragments was seen. For the unsymmetrical
bis-acetylides, the fragmentation pattern was often as-
sociated with the stepwise loss of different acetylide
ligands.
Table 2
UV–vis spectral data of ruthenium and osmium mono- and bis-
acetylides
a
Compound
umax (nm) log m
HCꢀC–Ph
HCꢀC–C6H4-p-CH3
HCꢀC–C6H4-p-NO2
trans-[(dppm)2Ru(Cl)(CꢀC–Ph)]
trans-[(dppm)2Ru(Cl)(CꢀC–C6H4-p-CH3)]
trans-[(dppm)2Ru(Cl)(CꢀC–C6H4-p-NO2)]
trans-[(dppm)2Ru(CꢀCPh)
(CꢀC–C6H4-p-NO2)] 7
246
251
286
316
313
476
480
4.22
4.18
4.13
4.19
4.14
4.21
4.26
Metal to acetylide charge transfer is a common spec-
tral feature of metal acetylide complexes and reflects
the p-electron conjugation in these complexes. [12] The
UV–vis spectra of the ruthenium and osmium acetylide
complexes have been studied to investigate the effect of
(i) electron donor and acceptor acetylides, (ii) different
auxiliary phosphine ligands on metal centres and (iii)
different metals. The lowest energy band of the com-
plexes is listed in Table 2. The metal acetylides, trans-
[(dppm)2M(Cl)(CꢀC–C6H5)] (M=Ru) and (M=Os)
displayed the lowest energy bands at around 315 nm
which were assigned as metal to acetylide charge trans-
fer. Replacement of aryl 4-H by 4-NO2 gave rise to a
trans-[(dppm)2Ru(CꢀC–C6H4-p-CH3)
(CꢀC–C6H4-p-NO2)] 8
483
320
4.25
4.47
trans-[(dppm)2Ru(CꢀCPh)
(CꢀC–C6H4-p-CH3)] 10
trans-[(dppe)2Ru(Cl)(CꢀC–C6H4-p-NO2)] 3
trans-[(dppe)2Ru(Cl)
(CꢀC–C6H3-o-CH3-p-NO2)] 4
483
491
4.28
4.20
trans-[(dppm)2Os(Cl)(CꢀC–Ph)]
trans-[(dppm)2Os(Cl)(CꢀC–C6H4-p-NO2)]
trans-[(dppm)6Os(CꢀCPh)
312
501
499
4.41
4.27
4.31
(–CꢀC–C6H4-p-NO2] 11
a Spectra were recorded in CH2Cl2 solutions.

202
M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
Fig. 1. The lowest energy absorption bands in the UV–vis spectra of
some ruthenium(II) mono- and bis-acetylides.
Fig. 2. Molecular structure of [(dppe)2Ru(Cl)(CꢀC–C6H4-p-NO2)] 3.
2.3. X-ray crystallography
previously reported [(dppe)2Ru(Cl)(CꢀC–C6H5)] com-
plex [6j]. The electron withdrawing NO2 group removes
electron density from the Ru–CꢀC system, thus making
the CꢀC bond distance longer. This observation is
consistent with the IR spectral data as the IR stretching
frequency of the CꢀC group was shifted to higher
frequency by 21 cm−1 when aryl 4-H was replaced by
NO2. The Cl–Ru–C and M–C–C bond angles are
176.2(1), and 175.3(4)°, respectively, which indicates
that the metal acetylides maintain linearity with respect
to Cl−.
Single, X-ray quality crystals of [(dppe)2Ru(Cl)-
(CꢀC–C6H4-p-NO2)] 3, [(dppe)2Ru(Cl)(CꢀC–C6H3-o-
CH3-p-NO2)] 4 and [(dppm)2Os(CꢀC–C6H4-p-CH3)
(CꢀC–C6H4-p-NO2)] 12 were obtained by diffusion of
hexane into a dichloromethane solution. The molecular
structures of 3, 4 and 12 are shown in Figs. 2–4,
respectively, and selected bond parameters for each
structure are listed in Tables 4–6, respectively. In 3,
ruthenium is octahedrally coordinated by two chelating
phosphines, i.e. Ph2PCH2CH2PPh2, one chloride and
one acetylide. The four phosphorus atoms occupy the
equatorial plane of the octahedron and the chloride and
acetylide adopt trans positions with respect to each
other. This geometry is consistent with that of other
recently reported ruthenium acetylides. The CꢀC bond
The Ru(II) centre also displays the expected octahe-
dral coordination in 4 but introduction of a CH3 group
in the ortho position of the substituted aryl unit changes
the electron density distribution in the Ru–C and CꢀC
˚
distance is 1.206(7) A which is longer than that of the
Table 3
Solvatochromism studies of some ruthenium and osmium bis-
acetylides
Solvent
umax of 7b
umax of 8c
umax of 11d
(nm)
(nm)
(nm)
Ethylacetate
Methanol
Acetone
464
467
480
495
493
501
506
499
a
a
474
475
a
a
Ethanol
Chloroform
Dichloro-
methane
485
480
487
484
Dimethyl-
formamide
482
486
504
a Insoluble in the examining solvents.
b 7, trans-[(dppm)2Ru(CꢀC–Ph)(CꢀC–C6H4-p-NO2)].
c 8, trans-[(dppm)2Ru(CꢀC–C6H4-p-CH3)(CꢀC–C6H4-p-NO2)].
d 11, trans-[(dppm)2Os(CꢀC–Ph)(CꢀC–C6H4-p-NO2)].
Fig. 3. Molecular structure of [(dppe)2Ru(Cl)(CꢀC–C6H3-o-CH3-p-
NO2)] 4.

M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
203
Table 5
˚
Selected bond lengths (A) and angles (°) for [(dppe)2Ru(Cl)(CꢀC–
C6H3-o-CH3-p-NO2)] 4
˚
Bond length (A)
Ru–C(1)
Ru–P(4)
Ru–P(1)
C(1)–C(2)
2.013(11)
2.365(3)
2.409(3)
1.189(14)
Ru–P(3)
Ru–P(2)
Ru–Cl
2.364(3)
2.405(3)
2.473(3)
1.470(2)
C(2)–C(3)
Bond angles (°)
C(1)–Ru–P(3)
P(3)–Ru–P(4)
P(3)–Ru–P(2)
C(1)–Ru–P(1)
P(4)–Ru–P(1)
C(1)–Ru–Cl
P(4)–Ru–Cl
P(1)–Ru–Cl
C(1)–C(2)–C(3)
86.6(3)
82.93(12)
98.07(12)
99.8(3)
97.59(12)
175.3(3)
92.53(12)
82.61(11)
171.3(12)
C(1)–Ru–P(4)
C(1)–Ru–P(2)
P(4)–Ru–P(2)
P(3)–Ru–P(1)
P(2)–Ru–P(1)
P(3)–Ru–Cl
83.1(3)
98.5(3)
178.14(12)
173.58(12)
81.24(11)
90.97(11)
85.89(11)
175.9(10)
P(2)–Ru–Cl
C(2)–C(1)–Ru
Fig. 4. Molecular structure of [(dppm)2Os(CꢀC–C6H4-p-NO2)(CꢀC–
C6H4-p-CH3)] 12.
shown to have an ordered structure in the centrosym-
metric space group P1 (no. 2) whereas the nitro/
bonds from those in [(dppe)2Ru(Cl)(CꢀC–C6H4-p-
NO2)] 3. The Ru–C bonds get longer, suggesting that
ligand to metal or metal to ligand charge transfer is
greater in this complex than that in [(dppe)2Ru(Cl)-
(CꢀC–C6H5)] and 3. The IR spectrum of the complex
also supports this fact by showing a shift to higher
frequency in the w(CꢀC) stretching vibration (Table
1). The metal to phosphorus bond lengths lie in the
¯
phenyl compound was considered to be disordered
about an inversion centre at the metal atom. In the
current nitro/toluene structure a similar problem is
present with only the terminal nitro and methyl sub-
stituents breaking the inversion symmetry. Attempts
to desymmetrise the structure by refining in the non-
(
centrosymmetric space group P1 no. 1) led to sub-
˚
range 2.364(3)–2.409(3) A, the metal to carbon bond
stantial ‘ghosting’ in the residual electron density
maps and instability in the refinements. These could
not be rectified by the imposition of bonding con-
straints and/or damping and thus we were forced to
conclude that the structure was genuinely disordered
with reversals of the directions of the p-nitro-
phenylethynyl and the p-tolylethynyl ligands through-
out the crystal.
˚
length of the acetylide ligand is 2.013(11) A and the
˚
CꢀC bond length is 1.19(1) A. These values are simi-
lar to those found for 3.
The X-ray analysis of 12 shows it to crystallise
with a triclinic unit cell that is essentially the same as
those reported previously for the dinitro [10b] and the
nitro/phenyl [10c] analogues. The dinitro species was
The geometry at osmium is distorted octahedral
with the principal distortions (70.15(4)°) being associ-
ated with the bite of the chelating phosphine. The
Table 4
˚
Selected bond lengths (A) and angles (°) for [(dppe)2Ru(Cl)(CꢀC–
C6H4-p-NO2)] 3
˚
Bond length (A)
Table 6
˚
Ru–C(1)
Ru–P(2)
Ru–P(4)
C(1)–C(2)
1.986(5)
2.354(1)
2.386(1)
1.206(7)
Ru–P(1)
Ru–P(3)
Ru–Cl
2.360(2)
2.366(2)
2.500(1)
1.442(7)
Selected bond lengths (A) and angles (°) for [(dppm)2Os(CꢀC–C6H4-
p-NO2)(CꢀC–C6H4-p-CH3)] 12
˚
C(2)–C(3)
Bond length (A)
Os–C(1)
Os–P(2)
C(2)–C(3)
2.066(4)
2.350(1)
1.470(5)
Os–P(1)
C(1)–C(2)
2.341(1)
1.158(5)
Bond angles (°)
C(1)–Ru–P(2)
P(2)–Ru–P(1)
P(2)–Ru–P(3)
C(1)–Ru–P(4)
P(1)–Ru–P(4)
C(1)–Ru–Cl
P(1)–Ru–Cl
P(4)–Ru–Cl
C(1)–C(2)–C(3)
80.70(14)
83.23(6)
95.52(6)
98.83(14)
98.66(6)
176.20(13)
89.65(5)
79.89(5)
174.4(5)
C(1)–Ru–P(1)
C(1)–Ru–P(3)
P(1)–Ru–P(3)
P(2)–Ru–P(4)
P(3)–Ru–P(4)
P(2)–Ru–Cl
87.00(13)
91.98(13)
178.51(4)
178.04(4)
82.58(6)
100.70(5)
91.40(5)
175.3(4)
Bond angles (°)
C(1)–Os–P(1)
C(1)–Os–P(2)
P(1)–Os–P(2)
C(1)–Os–C(1%)
P(2)–Os–P(2%)
C(1)–C(2)–C(3)
86.08(11)
81.51(10)
70.15(4)
180.0
180.0
174.1(4)
C(1)–Os–P(1%)
C(1)–Os–P(2%)
P(1)–Os–P(2%)
P(1)–Os–P(1%)
C(2)–C(1)–Os
93.92(11)
98.49(10)
109.85(4)
180.0
P(3)–Ru–Cl
C(2)–C(1)–Ru
177.6(3)

204
M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
drawal of electron density at a metal centre is a
synergistic interaction and depends on all the ligands
coordinated to the metal centre. Replacement of the
chloride in complexes trans-[(dppm)2RuCl2] and trans-
[(dppe)2RuCl2] by
a
(CꢀC–C6H4-p-NO2) ligand
caused an increase in the E1/2 std values by 0.04, and
0.14 V, respectively, and indicates that the RuII/III
centre in both complexes is destabilised towards oxi-
dation by the Cl− substitution as the –CꢀC–C6H4-p-
NO2 species is a more electron withdrawing unit than
Cl−. The relative destabilisation was again different
in both complexes suggesting that the electron density
at the metal centre depends on the coordinated phos-
phine ligands. Substitution of the remaining chloride
of trans-[(dppm)2Ru(Cl)(CꢀCC6H4-p-NO2)] by an
electron donor acetylide to give 7, stabilised the
ruthenium centre towards oxidation. Destabilisation
of the metal centre was observed when the chloride
was substituted by electron accepting nitro-acetylide
to form 9. The electrochemical data in Table 7
demonstrate the extent by which the electron density
Fig. 5. Cyclic voltammogram of [(dppm)2Ru(CꢀC–C6H5)(CꢀC–
C6H4-p-CH3)] 10.
˚
osmium–ethyne bond (2.066(4) A) is typical of a
metal to conjugated carbon centre linkage. The
˚
ethyne CꢀC bond distance of 1.158(5) A is noticeably
shorter than that observed in the ruthenium dinitro
analogue [10b] and reflects a greater retention of
triple bond character. Departures from linearity in the
Os–CꢀC–Ar linkages are small, being 177.6(3)° at
C(1), and 174.1(4)° at C(2), respectively. As 12 is ef-
fectively isomorphous with the ruthenium dinitro and
nitro/phenyl species, the packing of the molecules is
essentially the same, there being no intermolecular
contacts of note.
can change on going from
a
trans-dichloride
[L2RuCl2] to a trans-bis-acetylide [L2Ru(CꢀC–R)2].
For the [(dppm)2Ru(CꢀC–R)2] and [(dppe)2Ru(CꢀC–
R)2] systems, the range of E1/2 std values are 0.24 and
0.25 V, respectively. These results suggest that the
systems can be fine-tuned to have particular electro-
chemical properties.
2.4. Electrochemistry of Ru(II) acetylides
Table 7
Electrode potentials of some ruthenium(II) mono- and bis-acetylides
The electron transfer process for the RuII/III redox
couple in each complex was found to be quasi-re-
versible (DEp=60–100 mV and ipa/ipc=ca. 1) (Fig.
5). The shift in the relative electrode potentials (E1/2
std) were related to the change in electron density at
the metal centre. These electrochemical data are con-
sistent with previous published findings [12b] for
[(C5H5)Ru(PR3)(CꢀCR%)] (R=CH3, C6H5; R%=C6H5,
NO2) where electron density on the metal centre de-
pends on the electron-withdrawing and -donating
abilities of the acetylenic ligands. We have previously
observed that the oxidation potential is reduced when
chloride is replaced by electron donating ferrocenyl
fragments [14]. A comparison of the E1/2 std of the
Complex
DEp (mV) E1/2 stda (V)
trans-[(dppm)2RuCl2]
trans-[(dppm)2Ru(Cl)(CꢀC–C6H5)]
trans-[(dppm)2Ru(Cl)
70
80
75
0.09
−0.112
0.13
(CꢀC–C6H4-p-NO2)]
trans-[(dppm)2Ru(CꢀC–C6H4-p-NO2)
(CꢀC–C6H5)] 7
trans-[(dppm)2Ru(CꢀC–C6H4-p-NO2)
(CꢀC–C6H4-p-CH3)] 8
trans-[(dppm)2Ru(CꢀC–C6H4-p-NO2)2] 9 70
trans-[(dppm)2Ru(CꢀC–C6H5)
(CꢀC–C6H4-p-CH3)] 10
trans-[(dppe)2RuCl2]
trans-[(dppe)2Ru(Cl)(CꢀC–C6H5)]
trans-[(dppe)2Ru(Cl)
80
80
0.02
−0.01
0.17
−0.15
100
95
80
90
0.02
−0.05
0.16
complexes
trans-[(dppm)2RuCl2]
and
trans-
(CꢀC–C6H4-p-NO2)] 3
trans-[(dppe)2Ru(Cl)
[(dppm)2Ru(Cl)(CꢀC–C6H5)] showed that the RuII/III
redox couple was stabilised by ca. 0.20 V towards
oxidation for the latter (Table 7). This suggests that
the acetylide ligand is more electron donating than
the chloride. A comparison of the E1/2 std values of
the analogous trans-[(dppe)2RuCl2] and trans-
83
0.16
(CꢀC–C6H3-o-CH3-p-NO2)] 4
trans-[(dppe)2Ru(CꢀC–C6H4-p-CH3)2] 5
trans-[(dppe)2Ru(CꢀC–C6H4-p-NO2)2] 6
trans-[(dppe)2Ru(CꢀC–C6H5)
(CꢀC–C6H4-p-NO2)]
80
61
80
−0.09
0.23
0.08
trans-[(dppe)2Ru(CꢀC–C6H5)2]
80
−0.03
[(dppe)2Ru(Cl)(CꢀC–C6H5)] complexes indicated
a
a Scan rate 100 mVs−1. All E1/2 values referenced to ferrocene in
the same system.
lower degree of stabilisation (0.07 V) by the (CꢀC–
Ph) ligand. This suggested that the donation/with-

M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
205
3. Experimental
(CH2Cl2) 2074 (CꢀC); lH (CDCl3, 250 Hz) 2.28 (s,
3H, CH3), 2.6 (m, 8H, PCH2CH2P), 6.57 (d, 3J(H3-
H2) 8 Hz, 2H, H3), H2 protons overlap with diphos.
aromatic protons, 6.90–7.40 (m, 40H, C6H5); 31P{1H}
(CDCl3, 250 Hz) −91.3; m/z 1048.2 (M+) 1047.5.
3.1. General
All experiments were performed under nitrogen us-
ing standard Schlenk line techniques. Solvents were
predried and distilled from appropriate drying agents.
Solution IR spectra were recorded on a Perkin–Elmer
1710 Fourier-Transform IR spectrometer. The NMR
spectra were recorded on a Bruker AM-400 spectrom-
eter. The 31P{1H}-NMR chemical shifts are reported
downfield from an external trimethylphosphite stan-
dard. Microanalyses were carried out in the Depart-
ment of Chemistry, University of Cambridge and
FAB (+ve ion) mass spectra were recorded using a
Kratos MS60 spectrometer. The electrochemical inves-
tigations of the RuII/III redox couple in complexes
trans-[L2RuR2] {where L=dppm, dppe} were
recorded at 298 K in a standard three-electrode sys-
tem (platinum working/auxiliary electrodes and silver
wire as pseudo reference electrode) using a 0.1 M
[NBun4][BF4]/CH2Cl2 solution as electrolyte (Fc=0.47
V vs. Ag/Ag+ at 298 K in 0.1 M [NBu4n][BF4]/
CH2Cl2). The metal salts cis-[(dppm)2MCl2] (M=Ru,
Os) and trans-[(dppe)2RuCl2] and the alkynes were
prepared by published procedures [15,16], as were the
mono-acetylide complexes trans-[(dppm)2M(Cl)(CꢀC–
R)] (M=Ru, Os) [7e] and bis-acetylides trans-
[(dppm)2M(CꢀC–Ph)2] [6j] and trans-[(dppe)2Ru-
(CꢀC–C6H5)(CꢀCC6H4-p-NO2)] [9d].
3.2.3. trans-[(dppe)2Ru(Cl)(CꢀC–C6H4-p-C6H5)] 2
From the reaction of trans-[(dppe)2RuCl2] (0.29 g,
0.3 mmol), HCꢀC–C6H4-pC6H5 (0.160 g, 0.9 mmol)
and NaPF6 (0.151 g, 0.9 mmol), 0.253 g (76%) of 2
was isolated. (Found: C, 71.41; H, 5.14.
C66H57ClP4Ru requires C, 71.38; H, 5.17%); w cm−1
(CH2Cl2) 2071 (CꢀC); lH (CDCl3, 250 Hz) 2.6 (m,
8H, PCH2CH2P), 6.73 (d, 3J(H3-H2) 8 Hz, 2H, H3),
H2 protons overlap with diphos. aromatic protons,
6.95–7.47 (m, 47H, C6H5); 31P{1H} (CDCl3, 250 Hz)
−91.3; m/z 1110 (M+) 1110.
3.2.4. trans-[(dppe)2Ru(Cl)(CꢀC–C6H4-p-NO2)] 3
From the reaction of trans-[(dppe)2RuCl2] (0.29 g,
0.3 mmol), HCꢀC–C6H4-pNO2 (0.132 g, 0.9 mmol)
and NaPF6 (0.151 g, 0.9 mmol), 0.239 g (74%) of 3
was isolated. (Found: C, 65.28; H, 5.03.
C60H52ClNO2P4Ru · CH2Cl2 requires C, 64.77; H,
4.73%); w cm−1 (CH2Cl2) 2051 (CꢀC); lH (CDCl3,
3
250 Hz) 2.6 (m, 8H, PCH2CH2P), 6.43 (d, J(H3-H2)
9 Hz, 2H, H2), 7.93 (d, 3J(H2-H3) 9 Hz, 2H, H3) ,
6.80–7.30 (m, 40H, C6H5); 31P{1H} (CDCl3, 250 Hz)
−92.5; m/z 1079 (M+) 1079.
3.2.5. trans-[(dppe)2Ru(Cl)(CꢀC–C6H3-o-CH3-p-NO2)]
4
3.2. Syntheses
From the reaction of trans-[(dppe)2RuCl2] (0.29 g,
0.3 mmol), HCꢀC–C6H3-o-CH3-pNO2 (0.145 g, 0.9
mmol) and NaPF6 (0.151 g, 0.9 mmol), 0.235 g (72%)
3.2.1. Mono-acetylides of {(dppe)2Ru(II)Cl}
The mono-acetylide complexes were prepared by an
adaptation of the procedure [9d]. To a CH2Cl2 solu-
tion of the metal chloride, trans-[(dppe)2RuCl2], three
equivalents of the alkyne and three equivalents of
NaPF6 were added. The mixture was stirred for 5–7
days at r.t. The solution was filtered and the solvent
was removed in vacuo. The sticky solid was washed
three times with hexane (10 ml) to remove excess lig-
and and was then redissolved in CH2Cl2 (20 ml) and
treated with one equivalent of DBU for 3 h. The
solvent was then removed in vacuo and the com-
plexes were purified by washing the crude solid with
acetone (2×5 ml) and recrystallised from hex-
ane:dichloromethane (1:1) to yield microcrystalline
solids.
of
4 was isolated. (Found: C, 66.49; H, 4.98.
C61H54ClNO2P4Ru requires C, 66.94; H, 4.93%); w
cm−1 (CH2Cl2) 2029 (CꢀC); lH (CDCl3, 250 Hz) 1.6
(s, 3H, CH3), 2.6 (m, 4H, PCH2CH2P), 2.8 (m, 4H,
3
PCH2CH2P), 6.54 (d, J(H3-H2) 8.5 Hz, 1H, H2), 7.84
4
(d, J(H3-H5) 2.25 Hz, 1H, H5), 6.80–7.20 (m, 41H,
C6H5); 31P{1H} (CDCl3, 250 Hz) −91.8; m/z 1094
(M+) 1093.5.
3.2.6. trans-[(dppe)2Ru(CꢀC–C6H4-p-CH3)2] 5
This was prepared by following a method from our
earlier report [6j]. A mixture of Me3SnCꢀC–C6H5
(0.05 g, 0.05 mmol), trans-[(dppe)2RuCl2] (0.41 g, 0.15
mmol) and CuI (3 mg) in CH2Cl2 (25 ml) was
refluxed for 24 h under inert atmosphere. The solu-
tion was allowed to come to r.t. and the volume was
reduced to 5 ml and applied to a short neutral grade
II alumina column. Eluting the column with
dichloromethane resulted in a yellow solution which
was evaporated to dryness to afford a bright yellow
3.2.2. trans-[(dppe)2Ru(Cl)(CꢀC–C6H4-p-CH3)] 1
From the reaction of trans-[(dppe)2RuCl2] (0.29 g,
0.3 mmol), HCꢀC–C6H4-pCH3 (0.104 g, 0.9 mmol)
and NaPF6 (0.151 g, 0.9 mmol), 0.210 g (67%) of 1
was isolated. (Found: C, 69.91; H, 5.33.
C61H55ClP4Ru requires C, 69.88; H, 5.29%); w cm−1

206
M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
product. Yield: 0.038 g, 65%; (Found: C, 74.15; H,
5.79. C70H62P4Ru requires C, 74.52; H, 5.54%); w cm−1
(CH2Cl2) 2062 (CꢀC); 31P{1H} (CDCl3, 250 Hz) −87.1.
3J(H2-H3) 9 Hz, 4H, H3), 6.84–7.66 (m, 40H, C6H5);
31P{1H} (CDCl3, 250 Hz) −145.2; m/z 1162 (M+)
1161.
3.3.2. trans-[(dppm)2Ru(CꢀC–C6H4-pNO2)-
(CꢀCC6H4-p-CH3)] 8
3.2.7. trans-[(dppe)2Ru(CꢀC–C6H4-p-NO2)2] 6
This was prepared following a method reported by
Miguel et al. [17]. HCꢀC–C6H4-p-NO2 (0.044 g, 0.3
mmol) and AgBF4 (0.058 g, 0.3 mmol) were stirred for
20 min in a 3:1 mixture of dichloromethane and water
(30 ml) in the absence of light. trans-[(dppe)2RuCl2]
(0.097 g, 0.1 mmol) was added into the reaction mixture
and stirred for another 20 h. The solution was filtered
and the aqueous layer was removed. The organic layer
was stirred with 1 M aqueous Na2S2O7 for 0.5 h. It was
then separated and dried over magnesium sulphate.
After removal of the solvent under reduced pressure the
crude product was purified by column chromatography
on neutral grade II alumina using a 1:1 mixture of
dichloromethane and hexane as eluent. Yield: 0.053 g,
45%; (Found: C, 68.64; H, 5.10. C68H56N2O4P4Ru re-
quires C, 68.63; H, 4.74%); w cm−1 (CH2Cl2) 2043
(CꢀC); lH (CDCl3, 250 Hz) 2.6 (m, 8H, PCH2CH2P),
From the reaction of trans-[(dppm)2Ru(Cl)(CꢀC–
C6H4-p-NO2)] (0.210 g, 0.2 mmol), Me3SnCꢀC–C6H4-
pCH3 (0.061 g, 0.22 mmol) and CuI (5 mg) 0.106 g
(45%) of 8 was isolated (along with 0.018 g of 9 (8 %)).
(Found: C, 71.20; H, 4.98. C67H55NO2P4Ru requires C,
71.15; H, 4.86%); w cm−1 (CH2Cl2) 2054, 2080 (CꢀC);
lH (CDCl3, 250 Hz) 2.22 (s, 3H, CH3) 4.83 (m, 4H,
PCH2P), 6.08 (d, 3J(H3-H2) 9 Hz, 2H, H2), 7.77 (d,
3
3J(H2-H3) 9 Hz, 2H, H3), 6.08 (d, J(H7-H8) 8 Hz, 2H,
3
H7), 7.77 (d, J(H7-H8) 8 Hz, 2H, H8), 6.84–7.66 (m,
40H, C6H5); 31P{1H} (CDCl3, 250 Hz)−145.0; m/z
1131 (M+) 1130.
3.3.3. trans-[(dppm)2Ru(CꢀC–C6H5)(CꢀCC6H4-
p-CH3)] 10
From the reaction of trans-[(dppm)2Ru(Cl)(CꢀC–
C6H5)] (0.201 g, 0.2 mmol), Me3SnCꢀC–C6H4-pCH3
(0.061 g, 0.22 mmol) and CuI (5 mg), 0.099 g (46%) of
10 was isolated. (Found: C, 73.73; H, 5.16. C67H56P4Ru
requires C, 74.10; H, 5.16%); w cm−1 (CH2Cl2) 2069
(CꢀC); lH (CDCl3, 250 Hz) 2.21 (s, 3H, CH3) 4.83 (m,
3
3
6.64 (d, J(H3-H2) 9 Hz, 4H, H2), 7.99 (d, J(H2-H3) 9
Hz, 4H, H3), 6.83–7.40 (m, 40H, C6H5); 31P{1H}
(CDCl3, 250 Hz) −88.2.
3
4H, PCH2P), 6.20 (d, J(H3-H2) 8 Hz, 2H, H2), 7.75 (d,
3.3. Unsymmetrical bis-acetylides of Ru(II) and Os(II)
3J(H2-H3) 8 Hz, 2H, H3), 6.76–7.79 (m, 45H, C6H5);
31P{1H} (CDCl3, 250 Hz) −144.6; m/z 1083 (M+)
1085.
The unsymmetrical s-acetylide complexes featuring
dppm as chelating ligand were prepared by following a
general procedure outlined below for complex 7.
All the unsymmetrical bis-acetylide complexes of os-
mium were synthesised using the general procedure of
stirring
trans-[(dppm)2OsCl(CꢀC–C6H4–R)]
with
3.3.1. trans-[(dppm)2Ru(CꢀC–C6H5)(CꢀCC6H4-p-NO2)]
7 and trans-[(dppm)2Ru(CꢀC–C6H4-p-NO2)2] 9
Me3SnCꢀC–R%in THF in the presence of CuI for 20 h
under reflux.
To a solution of trans-[(dppm)2Ru(Cl)(CꢀC–C6H4-p-
NO2)] (0.21 g, 0.2 mmol) in THF (20 ml), Me3SnCꢀC–
C6H5 (0.58 g, 0.11 mmol) and CuI (3 mg) were added.
The reaction mixture was stirred for 3 h under reflux.
The solvent was then evaporated to dryness in vacuo
and the residue was purified by column chromatogra-
phy on neutral grade II alumina using a 1:1 mixture of
dichloromethane and hexane as eluent. The first red
band was identified as trans-[(dppm)2Ru(CꢀC–
C6H5)(CꢀCC6H4-p-NO2)] (7) in 49% yield (0.11 g);
(Found: C, 70.66; H, 4.84. C66H53NO2P4Ru requires C,
70.97; H, 4.74%); w cm−1 (CH2Cl2) 2054, 2079 (CꢀC);
lH (CDCl3, 250 Hz) 4.82 (m, 4H, PCH2P), 6.09 (d,
3.3.4. trans-[(dppm)2Os(CꢀC–C6H4-p-NO2)-
(CꢀC–C6H5)] 11
From the reaction of trans-[(dppm)2Os(Cl)(CꢀC–
C6H4-p-NO2)] (0.341 g, 0.33 mmol), Me3SnCꢀC–C6H5
(0.087 g, 0.33 mmol) and CuI (7 mg), 0.107 g (30%) of
11 was isolated. (Found: C, 62.48; H, 4.09.
C66H53NO2P4Os.CH2Cl2 requires C, 62.32; H, 4.26%); w
cm−1 (CH2Cl2) 2052, 2080 (CꢀC); lH (CDCl3, 250 Hz)
5.40 (m, 4H, PCH2P), 6.02 (d, 3J(H3-H2) 9 Hz, 2H, H2),
3
7.78 (d, J(H2-H3) 9 Hz, 2H, H3) 6.83–7.43 (m, 45H,
C6H5); 31P{1H} (CDCl3, 250 Hz) −191.4; m/z 1209
(M+) 1207.
3
3J(H3-H2) 9 Hz, 2H, H2), 7.78 (d, J(H2-H3) 9 Hz, 2H,
H3), 6.83–7.47 (m, 45H, C6H5); 31P{1H} (CDCl3, 250
Hz) −144.9; m/z 1116 (M+) 1116; and the second
band as trans-[(dppm)2Ru(CꢀCC6H4-p-NO2)2 (9) in
17% yield (0.04 g); (Found: C, 67.71; H, 4.40.
C66H52N2O2P4Ru requires C, 68.21; H, 4.47%); w cm−1
(CH2Cl2) 2052 (CꢀC); lH (CDCl3, 250 Hz) 4.85 (m, 4H,
PCH2P), 6.13 (d, 3J(H3-H2) 9 Hz, 4H, H2), 7.80 (d,
3.3.5. trans-[(dppm)2Os(CꢀC–C6H4-
p-NO2)(CꢀC–C6H4-p-CH3)] 12
From the reaction of trans-[(dppm)2Os(Cl)(CꢀC–
C6H4-p-NO2)] (0.113 g, 0.1 mmol), Me3SnCꢀC–C6H4-
p-CH3 (0.030 g, 0.11 mmol) and CuI (5 mg), 0.032 g
(27%) of 12 was isolated. (Found: C, 62.40; H, 4.23.
C67H55NO2P4Os.CH2Cl2 requires C, 62.58; H, 4.37%); w

M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
207
Table 8
Crystal data and structure refinement parametersa
Data
3
4
12
Empirical formula
Solvent
C60H52NO2P4ClRu
CH2Cl2
C61H54NO2P4ClRu
–
C67H55NO2P4Os
–
Formula weight
Colour, habit
Crystal size (mm)
Lattice type
1164.4
1093.5
1220.2
Yellow block
0.30×0.10×0.10
Triclinic
Red block
0.18×0.13×0.08
monoclinic
P21/n, 14
290
Deep red plate
0.26×0.08×0.04
Triclinic
(
(
Space group
P1, 2
P1, 2
Temperature (K)
Unit cell dimensions
153
293
˚
a (A)
13.910(3)
17.301(3)
13.685(3)
108.97(3)
119.41(3)
90.28(3)
2658.5(9)
2
13.478(3)
16.105(3)
24.088(5)
–
90.61(3)
–
5228(2)
4
1.389
9.808(2)
12.456(3)
12.760(4)
80.93(2)
68.40(2)
72.24(2)
1378.6(6)
1b
˚
b (A)
˚
c (A)
h (°)
i (°)
k (°)
3
˚
V (A )
Z
Dcalc. (g cm−3
F(000)
)
1.455
1196
1.470
616
2256
Diffractomer
Rigaku AFC7
Mo–Ka
0.61
Rigaku AFC5R
Mo–Ka
0.52
Siemens P4/PC
Cu–Ka
5.83
Radiation used
v (mm−1
)
Theta range for data collection (°)
Scan type
Reflections collected
2.5–22.5
v/2u
6923
2.5–22.5
v/2u
6839
3.7–63.0
v
4462
Reflections observed ꢀF0ꢀ\4|(ꢀF0ꢀ)
Absorption correction
Max./min. transmission
No. of variables
5598
2919
4396
Semi-empirical
1.00, 0.94
553
0.052
0.142
Semi-empirical
1.00, 0.87
535
0.072
0.134
Gaussian
0.80, 0.41
302
0.029
0.074
c
R1
wR2
d
Weighting factors a, be
0.112, 0.000
1.16, −1.72
0.055, 0.000
0.79, −0.57
0.039, 1.972
0.56, −1.08
−3
˚
Largest difference peak and hole (e A
)
a Details in common: graphite monochromated radiation, refinement based on F2.
b The molecule is disordered about a crystallographic centre of symmetry, see text.
c R1=SꢀꢀF0ꢀ−ꢀFcꢀꢀ/SꢀF0ꢀ.
d wR2=ꢁ{S[w(F02−Fc2)2]/S[w(F02)2]}.
e w−1=s2(F20)+(aP)2+bP.
cm−1 (CH2Cl2) 2051, 2083 (CꢀC); lH (CDCl3, 250 Hz)
2.22 (s, 3H, CH3), 4.83 (m, 4H, PCH2P), acetylide
aromatic protons were not clearly observed, 6.76–7.79
(m, 48H, C6H5); 31P{1H} (CDCl3, 250 Hz) −191.4; m/z
1218 (M+) 1220.
4. Crystallography
Table 8 provides a summary of the crystal data, data
collection and refinement parameters for complexes 3, 4
and 12. All three structures were solved by the heavy
atom method and all the non-hydrogen atoms were
refined anisotropically by full matrix least-squares
based on F2. In each structure all the pendant phenyl
rings were refined as idealised rigid bodies. In 4 and 12
the hydrogen atoms of the methyl groups attached to
sp2 centres were located from a DF map, idealised,
assigned isotropic thermal parameters, U(H)=1.5
Ueq(C), and allowed to ride on their parent atoms. The
remaining hydrogen atoms in all three structures were
placed in calculated positions, assigned isotropic ther-
mal parameters, U(H)=1.2 Ueq(C), and allowed to ride
on their parent atoms. Computations were carried out
using the SHELXTL PC program system [18].
3.3.6. trans-[(dppm)2Os(CꢀC–C6H5)(CꢀC–C6H4-
p-CH3)] 13
From the reaction of trans-[(dppm)2Os(Cl)(CꢀC–
C6H5)] (0.109 g, 0.1 mmol), Me3SnCꢀC–C6H4-p-CH3
(0.030 g, 0.11 mmol) and CuI (5 mg), 0.034 g (29%) of
13 was isolated. (Found: C, 67.07; H, 4.73.
C67H56P4Os.0.5CH2Cl2 requires C, 66.69; H, 4.69%); w
cm−1 (CH2Cl2) 2069 (CꢀC); lH (CDCl3, 250 Hz) 2.30
3
(s, 3H, CH3), 5.39 (m, 4H, PCH2P) 6.28 (d, J(H2-H3)
9 Hz, 4H, H2), 6.90 (d, 3J(H2-H3) 9 Hz, 4H, H3),
7.02–7.66 (m, 41H, C6H5); 31P{1H} (CDCl3, 250 Hz)
−195.0; m/z 1178 (M+) 1175.

208
M. Younus et al. / Journal of Organometallic Chemistry 578 (1999) 198–209
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Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 116212 and 115337 for com-
pounds 3 and 12, respectively. Compound 4 can be
found on the CCDC Database under code NABBEX.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (Fax: +44-1223-336-033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
Acknowledgements
The authors thank the Cambridge Commonwealth
Trust for a Scholarship and Shahjalal University of
Science and Technology, Bangladesh, for study leave
(MY), the British Council (MCBC), ICI, Wilton (AH
and NP) for financial assistance and Johnson Matthey
PLC (‘JM’) for the loan of precious metals.
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